Prefetching techniques are sometimes used to improve the functioning of computer systems by decreasing the amount of time required for the computer to perform certain tasks. In some computer systems, prefetching techniques are used to reduce the portion of an operation's latency that is perceptible to the system's user. For example, a web browser may perform “link prefetching” by downloading a document that the user is likely to access in the future before the user actually selects a link to access the document. If the user subsequently accesses the document, the computer system may be able to present the document to the user more quickly than would be the case if the document had not been prefetched. Thus, by initiating (or even completing) the process of requesting, retrieving, and storing the document before the user accesses the document, the system may be able to partially (or completely) hide the latency of downloading the document from the user.